Fabric treatment method

ABSTRACT

A method for treating a sulfur-containing fabric and sulfur-containing fabrics with excellent antimicrobial properties are disclosed. First an aluminum salt is added to a sulfur-containing fabric. That product is then rinsed. The rinsed product is combined with an antimicrobial. In one embodiment, the sulfur-containing fabric is combined with an aqueous solution of an oxidizing agent prior to the addition of the aluminum salt. Fabrics treated by the method retain excellent antimicrobial activity even after repeated washings.

RELATED APPLICATION

The present application is a continuation application of U.S. Ser. No.14/855,413 filed Sep. 16, 2015 which claims the benefit of U.S.Provisional Patent Application No. 62/052782 entitled Fabric TreatmentMethod filed on Sep. 19, 2014, the contents of both of which areincorporated herein in total by reference.

FIELD OF THE INVENTION

The invention relates to a method for treating a fabric that isparticularly useful for imparting wash durable antimicrobial and/oranti-odor properties to fabrics.

BACKGROUND OF THE INVENTION

For more than a decade now a great deal of attention has been focused onthe hazards of bacterial, fungal, and viral contamination from everydayexposures. What once was a primary concern for health care facilities,especially hospitals, and food processing/food preparation facilities,is now an everyday concern for most every business, the home, schools,public transportation and so on. More virulent and, oftentimes, drugresistant strains of pathogenic bacteria are being identified around theglobe. And, while such issues were once considered localized issues,they are now regional, nationwide, if not world-wide issues owing to theease and extent to which the people of the world travel, not to mentionthe world-wide market place for manufactured goods and, perhaps morecritically, produce and other foodstuff.

While pathogenic bacteria are certainly a major concern, they are notthe only concern. The world is flush with microorganisms that may notcause death or sickness; yet they impose upon or adversely impact ourlives on a daily basis. For example, molds can create an unsightlyappearance in or on our homes, especially in bathrooms and basements;certain bacteria may affect the smell and/or taste of our drinkingwater, other bacteria affect the smell of clothing, towels, upholsteryand other fabrics, etc.

Numerous efforts have been undertaken to ward off contamination and/ortransmission of such bacteria, fungi and other microorganisms.Specifically, much effort has been made to introduce antimicrobialperformance into a host of specialized and non-specialized products andarticles of manufacture, especially those comprising or associated withtouch surfaces. Such products and articles run the gamut, from cuttingboards to refrigerator linings, from door knobs to cellular telephonehousings, from HVAC units and components to medical devices such asstents, catheters and the like, from fabrics to wound care products,etc. This antimicrobial performance is achieved by either treating thesurface of the product or article with a coating containing anantimicrobial agent or directly incorporating the antimicrobial agentinto the material or composition from which the product or article ismade.

While many of these applications have achieved varying degrees ofcommercial and technical success, one particular application, fabrics,especially for apparel, has and continues to be an area of continualdevelopmental effort. Early on, manufacturers employed organicantimicrobial agents, most frequently triclosan, as an antimicrobialagent applied as a topical treatment or, more commonly, incorporatedinto the polymer melt from which the fibers/filaments are spun/extruded.However, the ability to incorporate triclosan into fiber materials islimited: showing success in acrylic and/or acetate fibers but not inpolyamides, polyesters, etc. The use of triclosan has also raisedcertain health and safety concerns, especially with respect to skinirritation and sensitivity to the chlorine and chlorides within thesecompounds as well as the possible bioabsorption of the triclosan and/orits components/degradation residues into the body. Furthermore,triclosan has poor longevity in these applications due to its mobilityin polymer compositions and the quickness with which it is washed out ofthe fabric.

The antimicrobial properties of a number of inorganic materials,especially metals such as silver, copper, zinc, mercury, tin, gold,lead, bismuth, cadmium, chromium and thallium, have long been known.Certain of these metals, especially silver, zinc, gold and copper, haveenjoyed greater success due to their relatively low environmental andtoxicological effects and high antimicrobial activity. In order toaddress some of the aforementioned problems with organic antimicrobialagents like triclosan, others have taken the approach of coating fibers,filaments and/or fabric with silver metal by, for example, vapordeposition or other plating techniques. These methods bind the silvermetal to the surface of the polymer fiber/filament. Antimicrobialperformance arises from the relatively slow oxidation of the surface ofthe silver metal and the subsequent availability/release ofantimicrobially active silver ions from the oxidized silver. Althougheffective and long lived, antimicrobial performance is poor to marginalowing to the slow rate at which the silver ions are generated:effectiveness being a function of the extent of ion generation and,hence, the rate of oxidation.

Further compounding the efficacy of silver metal is that fact thatwashing of the substrate or substrate surface removes all orsubstantially all of the oxidized silver. Consequently antimicrobialefficacy following washing is delayed until a sufficient level ofoxidation or other generation of silver ions occurs on the surface ofthe silver metal coating. Speed of oxidation is not the only concern;the costs of these silver coated materials are relatively high-thoughone can regulate the costs, at the expense of performance, by using lesssilver coated fiber in the fabric. Furthermore, fabrics made with thesematerials oftentimes have associated therewith a static nuisance owingto the electrical conductivity of the silver fibers. Finally, as wouldbe expected, the presence of the silver coated fibers affects the colorand feel of the fabric. Since these fibers do not absorb the dyes usedto color the fabric, they will always stand out. The degree of theirimpact on the color or visual image depends upon the content of silvercoated fiber in the fabric.

In an effort to address many of the aforementioned consequences andshortcomings of silver metal and organic antimicrobial agents, recentattention has been focused on the use of certain inorganic silvercompounds, complexes and the like. Suitable inorganic silverantimicrobial agents may take many different forms including simplesilver salts or complexes including wholly inorganic salts as well asorganometallic complexes. Other, and especially beneficial, complexforms include those antimicrobial agents comprising ceramic particleshaving ion-exchanged silver ions carried therein or thereon as well aswater soluble glasses that have incorporated therein various readilysoluble silver ion sources. Exemplary ion-exchange type antimicrobialagents include those wherein the ion-exchange carrier particles areceramic particles including zeolites, hydroxy apatites, zirconiumphosphates and the like. Antimicrobial agents based on zeolite carriersare disclosed in, for example, U.S. Pat. Nos. 4,911,898; 4,911,899;4,938,955; 4,906,464; and 4,775,585. Antimicrobial zirconium phosphatesinclude those disclosed in, for example, U.S. Pat. Nos. 4,025,608 and4,059,679 and the Journal of Antibacterial Antifungal Agents Vol. 22,No. 10, pp. 595-601, 1994. Finally, antimicrobial hydroxyapatitespowders include those disclosed in U.S. Pat. Nos. 5,009,898 and5,268,174, among others.

Although these antimicrobial agents have found growing success in theproduction of antimicrobial fabrics and enable excellent antimicrobialperformance, generally without the delay of the silver metal coatedfibers, they still have some of the same shortcomings as well as someadditional problems. For example, except for hydrophilic polymers, whenthe antimicrobial agent is incorporated into the original polymermaterial from which the fiber or fabric is made, only that portion ofthe antimicrobial agent at or proximate to the surface of the fiber orfilament made thereof is available to provide antimicrobial efficacy.Specifically, because these agents rely upon contact with water ormoisture to release and transport the antimicrobial silver ion, unlessthere are pores in the polymer or the polymer has hydrophiliccharacteristics, there are no transport pathways for the ions fromwithin the polymer. Consequently, with hydrophobic or insufficientlyhydrophilic amphiphilic materials, the manifestation of antimicrobialefficacy is limited to those antimicrobial agents in contact with thesurface of the fibers. Thus, depending upon the denier of the fibers,there is the possibility that much of the antimicrobial agent may bewasted and non-accessible, thereby adding costs without benefit. Ofcourse, this detriment is mitigated somewhat in those fabrics which areemployed in applications that are subject to wear because the erosiveeffect .of wear will expose previously entombed antimicrobial agent.But, then again, wear also means that the integrity of the fiber itself,especially its strength and, in clothing, insulating property andappearance will be adversely affected. While the issue of longevity isless of a concern for “single-use” disposable type articles orinfrequently laundered articles such as curtains, upholstery, etc., itis especially critical and of concern for fabrics used in apparel thatis likely to be washed quite frequently, if not following each use.Regardless, antimicrobial efficacy is limited inasmuch as only thoseantimicrobial metal ion sources that are exposed are available toprovide antimicrobial metal ions for antimicrobial performance. Thiscompares with those fibers, filaments and the like that are made withsufficiently hydrophilic polymers which enable ion transport from withinand throughout the fiber material. Here, all of the antimicrobial agent,even that entombed within the polymer, is available to contribute ionsto antimicrobial performance. Thus, less antimicrobial agent is requiredto achieve the same level of efficacy in hydrophilic materials ascompared to hydrophobic or insufficiently hydrophilic amphiphilicmaterials.

Another shortcoming of the inorganic silver antimicrobial agents,particularly those comprising the simple silver salts and other highlysoluble silver antimicrobial agents, is their short-lived nature.Because of the limited amount of antimicrobial agent at the surface, ahigh degree of solubility means that the full amount of antimicrobialactive at the surface can quickly be washed away or otherwise depleted.In hydrophilic materials, some of this loss is mitigated by iontransport of ions from within the polymer: though transport, and hencerelease, is limited by the rate of ion transport. And, as noted above,in all applications, those fibers that are subject to wear willseemingly replenish as the entombed antimicrobial agent is exposed atthe surface of the fibers and filaments; however, again, that which isnewly exposed is quickly depleted as well. Furthermore, because wear isnot typically even, replenishment only affects those areas subject toconstant wear. Thus, in the absence of a constant and even wear, whichalso means limited life to the fabric; antimicrobial efficacy slowlylessens over time as the exposed antimicrobial source is depleted.

In following, degree of performance and longevity of performance,especially as relates to wash-durability, have long been of notableconcern. Numerous efforts have been undertaken and incremental advanceshave been made to address these issues. U.S. Pat No. 6,607,994 pointsout that fabric treatments endowing particular characteristics oractivity are highly desired by the apparel, home furnishings, andmedical industries but conventional processes used to impart suchcharacteristics often do not lead to permanent effects. Laundering orwearing of the treated fabric causes leaching or erosion of the agentsresponsible for imparting the desired characteristics. Attempts toaddress the problem by using encapsulated nanoparticles that formcovalent bonds to the fabric have had limited success and, besides,functionalizing the nanoparticles and then chemically bonding them tothe fabric adds complexity and cost and is not suitable for mostapplications, particularly not for broad scale consumer application in,e.g., clothing, bedding, upholstery, and the like.

Trogolo et. al., U.S. Pat. No. 6,436,422, employed hydrophilic polymercoatings so as to enhance longevity by ensuring that all of theantimicrobial agent within the coating is available for providingantimicrobial efficacy. However, hydrophilic polymer fibers andhydrophilic polymer coated fibers have limited use due to the relativelypoor physical and performance properties of the hydrophilic polymermaterials themselves.

Hendriks et al., U.S. Pat. No. 7,754,625, made improvements in washdurability by using an antimicrobial agent that combined a water-solublezinc salt such as zinc oxide, and an antimicrobial metal ion source ofsilver and copper ions. They tested white polyester fabric and focusedon discoloration of the fabric. The samples showed good bioefficacy evenafter several wash cycles. This represented significant progress towardsthe problem but, it turns out, was not universal and encounters issueswith certain fabrics and/or dyed fabrics.

Specifically, it has now been found that certain chemicals or species ofchemicals that are inherently present in fibers or that are incorporatedand/or applied to fibers and fabrics have an adverse effect on ionicantimicrobial metals. In this regard, it is uncommon for a fabric not tobe subjected to some treatment either prior to or after incorporationinto an article of manufacture. Common treatments include dyes, sizings,etc. Dying is perhaps the most common treatment with sulfur dyes andindigo a couple of the most widely used dyes. Sulfur dyes are so namedbecause of the use of sulfur in their synthesis. They are commonly usedin the dying of cellulosic materials, especially cotton, and aretypically associated with dark colors such as blacks, browns and deepblues. C.I. Sulfur Black 1 is an example of a sulfur dye. Denim, perhapsone of the most ubiquitous fabrics of the day, is typically dyed withindigo, alone, or more commonly, with both indigo and a sulfur dye. Dueto growing concerns with the use of indigo dyes, especially from anenvironmental perspective, sulfur dyes are becoming even more criticaland prolific in the dying of denim with sulfur dyes soon expected tosurpass indigo as the key denim dye.

Although desirable and, oftentimes, necessary such treatments canfurther complicate the ability to impart antimicrobial activity tofabrics and, articles made therefrom. Specifically, these treatments arefound to contain chemical compounds which or whose degradation oroxidation products interfere with the antimicrobial agent, oftentimeschemically binding the metal ions so as to render them unavailable forantimicrobial performance. This is especially so with sulfur containingtreatments, especially sulfur dyes. Although its exact mechanism ofaction is uncertain, it is believed that the sulfur binds with and/orcomplexes with the antimicrobial metal ions: thereby negating theirantimicrobial efficacy.

However, this issue is not just limited to treated or dyed fabric.Indeed, certain fibers and fabrics, most especially wool and fabricsmade of or containing wool, manifest poor, if any, antimicrobialefficacy following treatment with antimicrobial metal ion typeantimicrobial agents. Further investigation has found that these fibers,most especially wool, naturally contain chemical compounds or species,particularly sulfur and sulfur containing compounds: thus, suffering thesame consequence of dyes and treatments containing like compounds andspecies.

Thus, while considerable effort has been expended in the development ofantimicrobial and anti-odor treatments for fabrics, problems continue.This is especially so for fabrics that are treated with and/or otherwisecontain sulfur, especially sulfur dyes.

Thus, there remains a need in the industry for a fabric that provideslong lasting antimicrobial and/or anti-odor performance, especially suchperformance with wash durability. In particular, there is a need forsulfur containing or treated fabrics that have long term antimicrobialand/or anti-odor properties which are not compromised or, ifcompromised, are minimally compromised by washing, particularly repeatedwashing

There also remains a need for a method, especially a simple and costeffective method, by which antimicrobial and/or anti-odor properties,particularly long lasting and wash durable antimicrobial and/oranti-odor properties, may be imparted to fabrics.

There especially remains a need for a method, especially a simple andcost effective method, by which antimicrobial and/or anti-odorproperties, particularly long lasting and wash durable antimicrobialand/or anti-odor properties, may be imparted to sulfur containing and/orsulfur treated fabrics.

SUMMARY OF THE INVENTION

The present teachings pertain to a process for improving theantimicrobial and/or anti-odor performance of fabric whose antimicrobialand/or anti-odor efficacy depends, in whole or in part, upon therelease, presence or generation of antimicrobial metal ions, whetherthrough oxidation, degradation, ion-exchange, dissociation,solubilization, and the like.

In a second respect, the present teachings pertain to a process forimparting antimicrobial and/or anti-odor properties to fabrics whichhave heretofore been found to be incapable of manifesting or manifestingadequate for consumer acceptance anti-microbial and/or anti-odorproperties even though the fabrics incorporate and/or have been treatedwith a typically or otherwise efficacious amount of an anti-microbialand/or anti-odor agent whose efficacy depends, in whole or in part, uponthe release, presence or generation of antimicrobial metal ions, whetherthrough oxidation, degradation, ion-exchange, dissociation,solublization, and the like due to an inhibition, interference orinteraction with the antimicrobial metal ions.

According to the present teachings, the processes described above entailtreating fabrics with one or more compounds which, or whose componentsor ions, complex with, sequester, bind, and/or react with, mostespecially preferentially complex with, sequester, bind, and/or reactwith, compounds or ions that are inherently, including naturally,present in the fabric and/or are imparted to the fabric though someprocess and/or treatment thereof and which otherwise inhibit the releaseor generation of, complex with, sequester, bind and/or react withantimicrobial metal ions, particularly in the presence of moisture,e.g., high humidity, washing, swimming, rain, sweating, etc. In aparticular embodiment, the present teachings pertain to a process bywhich fabrics, which inherently or as a result of other treatments, suchas dying, contain or have associated therewith sulfur and sulfurcompounds, are treated with compounds that complex with, sequester,bind, and/or react with, preferably in a preferential manner as comparedto the antimicrobial metal ions, the sulfur or sulfur containingspecies, especially sulfur containing ionic species.

In its preferred embodiment, the present teaching pertains to athree-step process in which sulfur containing fabrics are treated withan aluminum salt following which the treated material is rinsed/washedwith water or other suitable solvent, and, finally, the washed or rinsedmaterial is then treated with an antimicrobial metal ion-typeantimicrobial agent. This process is particularly suited for use in thetreatment of wool and/or fabrics that have been treated with sulfurdyes, most especially sulfur dyed denim. Preferably, the antimicrobialagent contains a source of silver ions, copper ions, zinc ions ormixtures of any two or all three ions. Optionally, though preferably,the aforementioned processes may further comprise treating the fabricwith an oxidizing agent prior to or concurrent with, preferably priorto, the aluminum salt treatment.

In another respect, the present teachings pertain to fabrics that havebeen treated according the foregoing processes. Most especially, thepresent teachings pertain to wool and/or fabrics that have been treatedwith sulfur containing compounds, especially sulfur dyes, which havebeen treated according to the foregoing processes.

In a preferred embodiment, the present teaching is directed to wooland/or sulfur dye treated fabrics, especially denim, which have beensubjected to a three-step process in which the wool or fabric is treatedwith an aluminum salt following which the treated material isrinsed/washed with water or another suitable solvent, and, finally, thewashed or rinsed fabric is then treated with an antimicrobial metalion-type antimicrobial agent. Optionally, though preferably, the fabricmay be subjected to a preconditioning or pretreatment wherein the fabricis treated with an oxidizing agent prior to or concurrent with,preferably prior to, the aluminum salt treatment.

According to yet another aspect, the present teachings pertain tofabrics that have improved antimicrobial and/or anti-odorproperties/performance as compared to similar fabrics which have notbeen subjected to an aluminum salt treatment prior to treatment with anantimicrobial metal ion-type antimicrobial/anti-odor agent.

According to yet another aspect, the present teachings pertain to sulfurcontaining and/or sulfur treated fabrics which manifest antimicrobialand/or anti-odor properties as a result of the incorporation therein orthe treatment thereof with an antimicrobial metal ion-typeantimicrobial/anti-odor agent. Most especially, there are provided wooland sulfur dyed fabrics manifesting antimicrobial and/or anti-odorproperties as a result of the incorporation therein or the treatmentthereof with an antimicrobial metal ion-type antimicrobial/anti-odoragent.

The fabrics processed in accordance with the present teachings provideexcellent antimicrobial and/or anti-odor activity which is retained evenafter repeated washings. Accordingly, and in particular, the presentteachings provide for antimicrobial and/or anti-odor sulfur containingor treated fabrics having excellent long term and wash durableantimicrobial and/or anti-odor properties.

DETAILED DESCRIPTION OF THE INVENTION

The invention relates to a method for treating a fabric in order toimpart and/or improve antimicrobial and/or anti-odor properties to thatfabric. In its most simplest of form the method comprises three keysteps. In an alternate embodiment, the method comprises four key steps.Depending upon the final product desired, other steps could be employedas well; however, the aforementioned steps are those necessary forimparting the desired antimicrobial/anti-odor performance to fabrics.

The present invention is applicable to all fabrics. As used in thisspecification and the claims, the term “fabric” is intended to meanfibers, yarns, cloths, textiles and finished goods made therefromincluding apparel, upholstery, etc. The fabric may be woven ornon-woven. The fabric may also be made from a variety of synthetic andnatural materials and blends thereof. Examples of synthetic materialsinclude nylons, polyesters and polyolefins. Examples of naturalmaterials include wool and cotton. Examples of blends includecotton-polyester, cotton-polyolefin, etc. Preferably, the fabric iscotton. For purposes of convenience, the invention will be described inrelation to sulfur containing fabric, most especially denim: though itis to be understood that the teachings are not and are not intended tobe so limited. Rather, the present teaching is applicable to any fabricwhich contains or has associated therewith ions and/or compounds whichin the presence of water dissociate to generate ions that have, anaffinity for antimicrobial metal ions, they complex with, sequester,bind, and/or react with the antimicrobial metal ions, especially wheresaid affinity leads to a loss and/or absence of antimicrobial and/oranti-odor performance.

By “sulfur-containing”, we mean that the fabric contains some form ofsulfur. The source of the sulfur can be naturally occurring such as inwool which contains sulfur-containing proteins. The source of the sulfurcan also be from additives used in the manufacture and/or treatment ofthe fabric. For example, the source of the sulfur can be from certainsulfur-containing enzymes used to treat the fabric. A more common sourceof sulfur in fabrics is sulfur dyes which are used in various amountsand at various stages of fabric manufacture and treatment.

Most preferably the fabric is denim. Denim is a woven fabric formed byinterlacing or intermeshing cotton yarns. The direction of weaving iscalled the “warp” direction, and the cross direction is called the“weft”. The weft yarns alternately go over and under the warp yarns. Thewarp yarn in denim is typically dyed, prior to weaving, with indigo, anaturally occurring blue dye, alone or in combination with a sulfur dye.Indigo dyeing can be performed to various depths of shade ranging fromlight blue to very dark blue or even black. The added sulfur dyeprovides additional shading and coloring possibilities to denim. Thoughstill prevalent, indigo dyes are coming under increased pressure due toenvironmental concerns and, hence, sulfur dyes are gaining importanceand use, especially in the dying of denim.

As used herein, when speaking of the load of various antimicrobial metalions in/on the ceramic carriers and/or their use rates, it is to benoted that the determination is made in terms of the ions as metal: forexample, grams of silver ions is determined as grams of silver metal.

Preferably, the fabric employed in the practice of the invention hasbeen dyed. Common dyes include vat dyes and sulfur dyes, alone or incombination. A vat dye is any of a large class of water-insoluble dyes,such as indigo and derivatives of anthraquinone. Commonly, the dye isapplied in a soluble, reduced form to impregnate the fiber and thenoxidized in the fiber back to its original insoluble form. Vat dyes areespecially fast to light and washing. Vat dyes date back severalcenturies and were so named because of the vats used in the reduction ofindigo plants through fermentation.

Sulfur dyes, named because of the use of sulfur in their synthesis, areused, for example, in dark colors such as blacks, browns and deep blues.C.I. Sulfur Black 1, CI Sulfur Brown 12, and CI Sulfur Red 6 are allexamples of sulfur dyes. Often, dependent upon the desired color, bothindigo and a sulfur dye are used in denim manufacture. Fabrics used inthe practice of the present invention have typically, and preferably,been dyed with a sulfur dye or with the combination of indigo and asulfur dye. Most preferably, the fabric is denim that has been dyed witha sulfur dye, alone or in combination with indigo.

Various dyeing techniques are used. For example, sulfur bottom refers totreatment with sulfur dyes before being dyed with indigo. Sulfur toprefers to treatment with sulfur dyes after being dyed with indigo andpure sulfur is when the sulfur dyes are used in the absence of indigo.Indigo itself does not contain sulfur. As a general rule, the amount ofsulfur and therefore the difficulties in imparting antimicrobialactivity to a fabric increase from sulfur bottom to sulfur top to puresulfur.

Optionally, though typically, fabrics to be employed in the practice ofthe present invention will have undergone other treatments prior tobeing subjected to the present treatment method. Exemplary treatmentsinclude sizing, dyeing and sewing to form garments. They may also havebeen subject to a desizing treatment wherein sizing, e.g., starch, isremoved rather than applied. This is commonly done by treatment with anenzyme which breaks down and releases the sizing agent.

Additionally, especially in the case of denim and other fabricssubjected to a “stressing process,” the fabric is often subjected to astonewashing process. The stonewashing process can use pumice stone,cellulosic enzymes, or sometimes an acid wash and is oftentimes used togive a worn or aged look to the fabric. Many of these prior treatmentsare done in a vessel washer.

Aluminum Salt Treatment

As noted, in its simplest embodiment, the process employs three steps.The first step involves treating a sulfur-containing fabric with analuminum salt. Typically the aluminum salt is an aqueous solution of thealuminum salt into which the fabric is placed: though the fabric couldbe sprayed with the solution as well. Most often, because the presentprocess may be, and preferably is, integrated into and/or immediatelyfollows other fabric treatment processes, especially the dying process,the fabric is treated with the aluminum salt agent in the same vessel,typically a washer, used in the previous treatments. For example, afterthe fabric is dyed, it is washed to remove excess dye. Once the wash iscompleted, the aluminum salt solution may be added to the washercontaining the fabric or the fabric, if it were first removed, could beadded to the washer vessel containing the aluminum salt solution.

Suitable aluminum salts are soluble salts, most especially andpreferably water soluble aluminum salts. Exemplary aluminum saltsinclude aluminum sulfates, aluminum phosphates, aluminum hydroxides,aluminum oxides, aluminum halides, and aluminum carboxylates andhydrates of the foregoing as well as mixtures of two or more of theforegoing. Preferred aluminum salts are the carboxylates, especiallyaluminum citrate and aluminum acetate. Aluminum halides, like aluminumchloride are acceptable, but are less preferred because of possiblereactions with water, especially in the case of aluminum chloride.Additionally, the aluminum salt can have a mixture of anionic moieties.For example, the aluminum salt can have both hydroxide and acetateanions as in basic aluminum diacetate, HOAl(AcO)₂ or basic aluminummonacetate, (HO)₂Al (AcO). The aluminum salt can also have a mixture ofcations such as in aluminum potassium sulfate, AlK(SO₄)₂. Insolublealuminum salts, such as aluminosilicates and zeolites are not includedunless they can be solubilized without adversely affecting the outcomeor performance of the claimed process. For example, certain watersoluble acids, such as citric acid at appropriate concentrations, willdissolve zeolite; hence a proper aqueous citric acid solution ofdissolved zeolite is contemplated. Preferred aluminum salts are aluminumsulfate, aluminum acetate, and aluminum citrate and hydrates thereof.Most preferably, the aluminum salt is hydrated aluminum sulfate becauseit is gives good results, is readily available and economical.

It is also to be appreciated that the aluminum salt and/or aluminum ionsmay be generated in-situ or as part of the treatment step. For example,aluminum metal could be treated with an acid, such as hydrochloric acidor, a suitable basic material, such as sodium hydroxide, to dissolve thealuminum metal. Additionally, as mentioned in the previous paragraph,certain insoluble aluminum salts or materials, such as zeolite, can bedissolved in acid solutions to form the aluminum salt. Accordingly,reference herein to aluminum salts is intended to include in-situ formedaluminum salts and in-situ formed salt-forming ions as well.

Preferably, the aluminum salt is dissolved in water prior to beingcombined with the sulfur-containing fabric. The concentration ofaluminum salt in water can vary but is preferably from about 0.1 toabout 30% by weight. Lower levels are sometimes less effective and, whentoo low, ineffective and higher levels add unnecessarily to the cost.More preferably the concentration is from 0.5 to 15% and most preferablyfrom 1 to 10%.

Generally speaking, the aluminum salt is allowed to contact thesulfur-containing fabric for a sufficient period of time to negate theadverse impact of those chemical species, especially sulfur, thatinterfere with or compromise the performance of the antimicrobial agentsand/or the ability to treat fabrics with such antimicrobial agents.Generally, the contact time can vary widely, but is preferably fromabout one minute to about two hours. Shorter time may give inadequatecontact time, thereby enabling some residual interference or degradationwith the antimicrobial performance as compared to those fabrics that aretreated for a longer period of time. Similarly, longer time, in excessof two hours, may be employed but is believed to be unnecessary and addstime and cost to the process. More preferably, the contact time is fromabout 10 to about 60 minutes.

Similarly, the temperature at which the aluminum salt treatment isperformed may vary widely as well and is typically in the range of fromabout 10° C. to about 90° C. Cooling or heating, though, add costs andhence it is preferred that the treatment be conducted in the range offrom about 20° C. to about 50° C. In essence, the process can be run atroom temperature for the production facility in which the treatment isconducted; thereby avoiding unnecessary costs of cooling and heating.

Oxidizing Agent Pretreatment

Optionally, though preferably, one may employ an oxidizing, step priorto performing the aluminum salt treatment. It has been found, at leastwith certain fabrics, that pre-treating the fabric with an oxidizingagent prior to performing the aluminum salt treatment facilitates andenhances the effect of the aluminum treatment step. Though not intendingto be bound by theory, it is believed that the oxidizing agent oxidizesthose species, especially the sulfur, responsible for the interferencewith the antimicrobial performance rendering them more susceptible toneutralization or binding with the aluminum salt. This step isespecially preferred when there are high levels of sulfur in the fabricor when the sulfur is especially accessible because a sulfur dye hasbeen applied either as the sole dye as in pure sulfur treatment or in asecondary dyeing operation as in a sulfur top treatment.

The oxidizing pretreatment step is conducted in a like manner to thealuminum salt treatment, but using a suitable oxidizing agent in anaqueous medium, preferably water. Suitable and preferred oxidizingagents include bromates such as sodium bromate, hydrogen peroxide,percarbonates such as sodium percarbonate, perborates such as sodiumperborate, persulfates such a potassium persulfate and hydrates of theforegoing as well as mixtures of two or more of the foregoing.Hypochlorites such as sodium hypochlorite, also known as bleach, can beused but they are less preferred because they often have an adversereaction with any dyes in the fabric. Sodium percarbonate is morepreferred because it gives good results, is readily available andeconomical.

The concentration of oxidizer in water can vary but is preferably fromabout 0.05 to about 10% by weight. Lower levels are sometimes lesseffective and, when too low, ineffective and higher levels addunnecessarily to the cost. More preferably the concentration is from 0.1to 7%, most preferably 0.2 to 5%. The contact time and temperature atwhich the pre-treatment is conducted is the same as for the aluminumtreatment, as recited above.

Post Treatment Rinse

The second key step to the claimed process is that in which the fabricresulting from the aluminum salt treatment is rinsed with an aqueousmedium, preferably water. In this step, the fabric is removed from thealuminum salt solution, either by draining the aluminum salt solutionfrom the treatment vessel or by removing the treated fabric from thetreatment vessel. In a preferred embodiment, especially from an economicand environmental standpoint, the fabric is subjected to wringing,spinning or centrifugation to remove excess solution from the fabric:the solution being added back to the original solution for reuse.Thereafter the fabric is rinsed one or more times, preferably withwater. Preferably, the fabric is immersed in water, with or withoutagitation: immersion being attained by adding the fabric to a vessel ofwater or adding water to a vessel containing the fabric. Alternatively,one may use a spin rinse cycle, as in a consumer washing machine wherewater is sprayed as the fabric is spun using both water and centrifugalforces to wash or rinse the aluminum salt treatment solution from thefabric. Preferably, the aforementioned immersion technique is employed.

The amount of water to be used in the rinse step is typically from 1 to500 times the weight of aluminum treated fabric. Lower amounts often donot give a sufficient rinse. Higher amounts are unnecessary and add tothe cost. More preferably, the amount of water is from 2 to 250 timesthe weight of the fabric. Preferably, the rinse is done for 0.5 to 60minutes, more preferably from 1 to 30 minutes. As noted above, the rinsecan be done by passing water through the solid product or by a singleimmersion or a series of two or more immersions, with the secondimmersion in clean(er) water. When the amount of water to be used is onthe lower end of the aforementioned range, immersion is preferred as thepass through method is not likely to fully remove the aluminum salttreatment which can lead to less than desired results in antimicrobialperformance. Additionally, in the case of multiple immersions in aseries of vessels, in order to save on water, one can discard thecontents of the initial immersion vessel after a given number of batchesof fabric have been rinsed and move the contents of the subsequentvessel to that vessel, doing the same for each subsequent vessel ifapplicable, and add fresh water to the last of the immersion vessels.Although not critical, it is preferred to wring, spin or centrifuge therinsed fabric before moving to the next vessel to minimize carryover ofthe higher concentration aluminum salt. If a single immersion vessel isemployed, it may be preferred to perform repeat the immersion rinse oneor more times to ensure good removal of the aluminum salt. Mostpreferably, the rinse is done by immersion with agitation.Alternatively, one may also use a combination of rinse methods:performing an immersion to remove the majority of the aluminum saltsolution followed by a spray rinse type method where water is passedthrough the fabric, much like the wash/spin cycle of a conventionalwashing machine. Following rinsing, the fabric is preferably subjectedto wringing, spinning, or centrifugation in order to remove excess waterand leave the fabric in a state where it will more readily absorb theantimicrobial agent solution.

Antimicrobial Treatment

The third key step of the present process is that in which the rinsedfabric is treated with an antimicrobial agent. Suitable antimicrobialagents are those that comprise antimicrobial metals and/or metal ions,especially those based upon or which readily release or generate metalions through oxidation, degradation, ion-exchange, dissociation,solubilization, and the like: the latter collectively referred to as the“antimicrobial metal-ion type” antimicrobial agents.

Preferred antimicrobial metal-ion type antimicrobial agents include a)antimicrobial metal ion containing, ion-exchange agents; b) watersoluble salts which, in the presence of water, dissociate to generatefree antimicrobial metal ions and c) water soluble glass particlescontaining free antimicrobial metal ions or water soluble salts which,in the presence of water, dissociate to generate free antimicrobialmetal ions: altogether. Antimicrobial metal ions include, but are notlimited to, silver, copper, zinc, gold, mercury, tin, lead, iron,cobalt, nickel, manganese, arsenic, antimony, bismuth, barium, cadmium,chromium and thallium. However, given the intended end use applications,the preferred antimicrobial metal ions are silver, copper, gold, andzinc and combinations thereof. Silver ions, alone or in combination withcopper or zinc or both, are more preferred due to the fact that theyhave the highest ratio of efficacy to toxicity, i.e., high efficacy tolow toxicity, and are comparatively more cost effective than gold.

The antimicrobial agent can be in the form of a simple salt of theantimicrobial metal such as the oxide, sulfide, chloride, bromide,carbonate, nitrate, phosphate, dihydrogen phosphate, sulfate, oxalate,acetate, benzoate, thiosulfate and the like. Specific examples includesilver nitrate, cupric oxide, cupric sulfate, copper acetate, silveracetate, and zinc acetate.

While the simple salts are effective, for applications where long termutility is desired and the substrate to which the composition is to beapplied is to be subjected to washing, especially on a repeated basis,it is preferred that the antimicrobial agent be either a water solubleglass or an ion-exchange type agent. These agents are especially desiredas they have and enable a much more controlled and timed release of theantimicrobial metal ion as opposed to the water soluble compounds.Alternatively, it may be desired to use a combination of the simplesalts and the water soluble glass and/or the ion-exchange type agentswhereby the former provides for a prompt, high level release ofantimicrobial metal ion and, hence, performance and the latter a moremoderate and longer lived antimicrobial metal ion release and, hence, alonger performance.

Antimicrobial water soluble glasses, especially the silver glasses, arecommercially available, and are described in, e.g., Ishii et. al.—U.S.Pat. No. 6,831,028; Namaguchi et. al. U.S. Pat. No. 6,939,820;Nomura—U.S. Pat. No. 6,593,260; Shimono et. al.—U.S. Pat. Nos. 5,290,544and 5,766,611; Gilchrist—U.S. Pat. No. 5,470,585 and US 20010006987 A1;Drake—U.S. Pat. No. 4,407,786; and Hikata et. al.—U.S. Pat. No.6,410,633; which are incorporated herein by reference in their entirety.They are characterized as being similar to typical glasses except thatthe traditional glass former, silicon dioxide, is replaced, in whole orin part, with phosphorus pentoxide (P₂O₅) and/or boric oxide (B₂O₃) as aprincipal glass former. Other oxides employed, typically in combinationwith one or both of the foregoing, in forming water soluble glassesinclude, for example, CaO, Na₂O, MgO, Al₂O₅, ZnO, etc. Typically thesecompositions will have from about 35 to about 75 mole percent,preferably from about 40 to about 60 mole percent, of the phosphorouspentoxide or the boric oxide and from about 5 to about 55 mole percent,preferably from about 10 to about 40 mole percent, of another metaloxide, e.g., a Group IA or Group IIA metal oxide such as sodium oxide orcalcium oxide, with silicon dioxide as the remaining or predominantremaining component. Where both phosphorus pentoxide and boric oxide arepresent, the two in combination will account for from about 40 to about85 mole percent, preferably from about 50 to about 80 mole percent, ofthe water soluble glass composition. Antimicrobial properties areachieved by incorporation of water-soluble, simple metal salts of silverand/or copper, such as silver oxide, silver acetate, cupric oxide, andcopper acetate. These antimicrobial additives are typically incorporatedinto/present within the water soluble glass in the range of from about 1to about 20%, preferably from about 3 to about 15%, by weight based onthe total weight of the antimicrobial water soluble glass.

Antimicrobial water soluble glasses are available from a number ofsources including Ishazuka Glass Co., Ltd., the latter selling silverglass under the tradename “lonpure.” Antimicrobial glasses dissolveand/or swell upon exposure to water, including, though more slowly,atmospheric moisture, thereby releasing or making available theantimicrobial metal ion source within the glass. By suitable adjustmentof the glass composition, the dissolution rates in water can becontrolled, thereby controlling the release of the antimicrobial metalions and, hence, extending their longevity.

Alternatively, the antimicrobial agent may be in the form of anion-exchange type antimicrobial agent or combinations of such agents.Ion-exchange type antimicrobial agents are typically characterized ascomprising an ion-exchange capable ceramic particle having ion-exchangedantimicrobial metal ions, i.e., the antimicrobial metal ions have beenexchanged for (replaced) other non-antimicrobially effective ions inand/or on the ceramic particles. While these materials may have somesurface adsorbed or deposited metal, the predominant antimicrobialeffect is as a result of the ion-exchanged antimicrobial metal ionsreleased from within the ceramic particles themselves.

Antimicrobial ceramic particles include, but are not limited tozeolites, calcium phosphates, hydroxyapatite, zirconium phosphates andother ion-exchange ceramics. These ceramic materials come in many formsand types, including natural and synthetic forms. For example, the broadterm “zeolite” refers to aluminosilicates having a three dimensionalskeletal structure that is represented by the formula:ZM_(2/n)O—Al₂O₃—YSiO₂—ZH₂O wherein M represents an ion-exchangeable ion,generally a monovalent or divalent metal ion; n represents the atomicvalence of the (metal) ion; X and Y represent coefficients of metaloxide and silica, respectively; and Z represents the number of water ofcrystallization. Examples of such zeolites include A-type zeolites,X-type zeolites, Y-type zeolites, T-type zeolites, high-silica zeolites,sodalite, mordenite, analcite, clinoptilolite, chabazite and erionite.The present invention is not restricted to use of these specificzeolites.

Generally speaking, the ion-exchange type antimicrobial agents used inthe practice of the present invention are prepared by an ion-exchangereaction in which non-antimicrobial ions present in the ceramicparticles, for example sodium ions, calcium ions, potassium ions andiron ions in the case of zeolites, are partially or wholly replaced withthe antimicrobial metal ions, for example, copper and/or silver ions.The combined weight of the antimicrobial metal ions will be in the rangeof from about 0.1 to about 35 wt. %, preferably from about 1 to 25 wt.%, more preferably from about 2 to about 20 wt. %, most preferably, fromabout 2.5 to 15 wt. %, of the ceramic particle based upon 100% totalweight of ceramic particle. Where the ceramic particles include two ormore different antimicrobial metal ions, each antimicrobial metal ion istypically present in and amount of from about 0.1 to about 25 wt. %,preferably from about 0.3 to about 15 wt. %, most preferably from about2 to about 10 wt. % of the ceramic particle based on 100% total weightof the ceramic particle.

Although any of the above-mentioned antimicrobial metal ions may beemployed, the preferred antimicrobial metal ions are zinc, copper andsilver, as well as combinations of any two or all three. Where thefabric to be treated is a light colored fabric, either by its naturalcoloration or by dying, most especially if the fabric is white, it ispreferred to use a combination of silver and copper ions, with orwithout zinc ions. In these instances, the weight ratio of silver tocopper ions is from 1:10 to 10:1, preferably from 5:1 to 1:5, mostpreferably from 2.5:1 to 1:2.5. In an especially preferred embodiment,the ceramic particle contains from about 0.3 to about 15 wt. % of silverions and from about 0.3 to about 15 wt. % of copper ions in a weightratio of 5:1 to 1:5. Exemplary compositions are disclosed in Hendrikset. al.—US 2006/0156948A1 and 2008/0152905A1, both of which areincorporated herein by reference in their entirety.

The antimicrobial ceramic particles may also contain other ion-exchangedions for various purposes, particularly ions that improve colorstability of the fabrics and/or overall stability and/or ion releasecharacteristics of ceramic particles. An exemplary and preferred otherion is ammonium ion. It is believed that ammonium ions aid in colorstability of the substrates to which they are applied. These other ions,especially the ammonium ions, may be present at a level of up to about20 wt. %, based on the total weight of the ceramic particle. Preferably,however, it is desirable to limit the content of ammonium ions to fromabout 0.1 to about 2.5 wt. %, more preferably from about 0.25 to about2.0 wt. %, and most preferably from 0.5 to about 1.5 wt. %, of theceramic particles.

Antimicrobial silver hydroxyapatites are available from Sangi CompanyLtd. of Tokyo, Japan under the tradename Apacider. These and otherantimicrobial hydroxyapatite materials are made by a number of knownprocesses including those disclosed in Sakuma et. al.—U.S. Pat. Nos.5,009,898 and 5,268,174. Antimicrobial silver zirconium phosphates areavailable from Milliken Chemical Company of Spartenburg, South Carolina,US, under the tradename AlphaSan. These and other antimicrobialzirconium phosphates are made by a number of known processes includingthose disclosed in Tawil et. al.—s Pat. No. 4,025,608; Clearfield—U.S.Pat. No. 4,059,679; Sugiura et. al.—U.S. Pat. No. 5,296,238; and Ohsumiet. al.—U.S. Pat. No. 5,441,717 and 5,405,644, as well as in the Journalof Antibacterial and Antifungal Agents, Vol. 22, No. 10, pp. 595-601,1994.

The preferred antimicrobial ion-exchange agents are the antimicrobialaluminosilicates, specifically the zeolites. A number of differentgrades and types of antimicrobial zeolites are commercially availablefrom Sciessent, LLC of Wakefield, Massachusetts, US under the AgIONtrademark. These include the following grades: AW1OD—about 0.6% silver;AG10N and LG10N—about 2.5% silver; AJ10D—about 2.5% silver, 14% zinc,and 0.5% -2.5% ammonium ions; and AC10D—about 6.0% copper and about 3.5%silver: These are based on a type A zeolite of a mean average diameterof about 3μ, 10μ in the case of the LG grade. Such antimicrobialzeolites and their production are disclosed in, among others, Hagiwaraet. al.—U.S. Pat. Nos. 4,911,898; 4,911,899; and 4,775,585; Niira et.al—U.S. Pat. Nos. 4,938,955 and 4,938,958; and Yamamoto et al.—U.S. Pat.No. 4,906,464.

It is to be appreciated that more than one antimicrobial agent may beemployed in the practice of the present process. For example, two ormore of the same type of antimicrobial agents may be used, e.g., two ormore simple salts, two or more ion-exchanged zeolites, etc. Similarly,combinations of different antimicrobial agents may be used, e.g., acombination of a water soluble glass and a zeolite or a combination of asimple salt and a zeolite. Additionally, where a plurality of sources ofthe antimicrobial metal ions are employed, one may provide one or morespecific metal ions and the other another one or more specific metalions. Alternatively, where it is desired to have two different ions, oneof which is in excess of the other, e.g., the combination of silver andcopper as noted above, one may use a silver salt in combination with asilver/copper zeolite. All such iterations are within the scope of thepresent teachings.

While the aforementioned antimicrobial agents are typically employed intheir neat form, i.e., as the salt or particle, it is also contemplatedthat they may be employed in an encapsulated form wherein discreteparticles of each are individually coated with a hydrophilic material ora plurality of particles of each or, in the case of multipleantimicrobial agent, of the combination are dispersed in discreteparticles of a hydrophilic material. Of course, in both cases, it isalso contemplated that only one component of the antimicrobial agent beencapsulated and the other employed in its neat form.

In one preferred embodiment, the antimicrobial agent is encapsulated ina hydrophilic polymer. The hydrophilic polymer used to encapsulate theantimicrobial agent is a polymer that can absorb sufficient water toenable the encapsulated particle to exhibit good antimicrobial behavior,i.e., to allow for the migration and release of the antimicrobial activeagent. The polymer will be characterized by having water absorption atequilibrium of at least about 2% by weight measured by ASTM D570.Preferably, the polymer will have a water absorption capacity atequilibrium of at least about 5% by weight. More preferably, the polymerwill have water absorption at equilibrium of at least about 20% byweight. Especially suitable hydrophilic polymers include those havingwater contents of from about 50 and to about 150% by weight

Typically the polymeric compositions useful as the encapsulatingmaterial are those which include substantial quantities of monomershaving polar groups associated with them, such that the overallpolymeric composition is rendered hydrophilic. The polar groups can beincorporated into the polymer main chain as in, for example, polyesters,polyurethanes, polyethers or polyamides. Alternatively or in addition,the polar groups can be pendant to or grafted onto the main chain as infor example, polyvinyl alcohol, polyacrylic acids or as in ionomers suchas Surlyn®. Surlyn® is available from Dupont and is the random copolymerpoly(ethylene-co-methacrylic acid) wherein some or all of themethacrylic acid units are neutralized with a suitable cation, commonlyNa⁺ or Zn⁺². While not being limited by way of theory, it is believedthat the inclusion of polar groups allows water to more readily permeatethe polymer and consequently, to allow slow transport of the metal ionthrough the encapsulating polymer layer.

Exemplary hydrophilic polymers useful as the encapsulating materialinclude, but are not limited to, (poly)hydroxyethyl methacrylate,(poly)hydroxypropyl methacrylate, (poly)glycerol methacrylate,copolymers of hydroxyethyl methacrylate and methacrylic acid,polyacrylamide, hyaluronan, polysaccharides, polylactic acid, copolymersof lactic acid, (poly)vinyl pyrrolidone, polyamides such as Nylon 6,6 orNylon 4,6 or Nylon 6,12, cellulosics, polyureas, polyurethanes andcertain polyesters containing a high percentage (at least about 10% byweight, preferably at least about 25% by Weight or more) of polyalkyleneoxide. The hydrophilic polymer may be a copolymer containing at least asubstantial amount of at least one or more of the above-mentionedhydrophilic monomers, including, for example, styrene/methacrylicacid/hydroxyethyl methacrylate copolymers, styrene/methacrylicacid/hydroxypropyl methacrylate copolymers,methylmethacrylate/methacrylic acid copolymers, ethylmethacrylate/-styrene/methacrylic acid copolymers and ethylmethacrylate/methyl methacrylate/styrene/methacrylic acid copolymers,copolymers based upon the cellulosics, and copolymers which utilizevinylpyrrolidone monomers, among numerous others.

Other hydrophilic polymers that may be used to encapsulate theantimicrobial metal ions include polyvinyl acetate, polyvinyl alcohol,and copolymers of polyvinyl alcohol and polyvinylacetate,polyvinylchloride, copolymers of polyvinylacetate and polyvinylchlorideand hydroxyl-modified vinyl chloride/vinyl acetate copolymers.Polyurethanes containing a high percentage (at least about 10% byweight, preferably at least about 25% by weight or more) of polyalkyleneoxide are especially useful to encapsulate the antimicrobial metal ions.Methods of encapsulation are described in U.S. Pat. No. 7,357,949,incorporated herein by reference.

The amount of encapsulating material will vary widely depending upon theintended application and, more importantly, the type of encapsulationemployed. In the case of individually encapsulated antimicrobialparticles, the microcapsule will typically have a coating thickness ofup to 15μ of hydrophilic polymer, preferably a coating thickness of 1 to10μ. While thicker coatings could be used efficaciously, concern mustthen be given to the impact, if any, of the presence of the hydrophilicpolymer on the properties of the matrix resin into which theencapsulated particles and the speed with which the antimicrobial metalions are able to release from the particles. In the case ofmicrocapsules containing multiple antimicrobial particles, themicrocapsules will typically have a mean average diameter of up to andover 2000μ, but generally not over 3000μ; preferably from about 15 toabout 1000μ, more preferably from about 50 to about 300μ, mostpreferably from about 90 to about 200μ. Here, concern is not only givento the speed and efficiency in which the antimicrobial metal ions areable to release from the particles, but to the overall feel of thefabric into which they are applied. Larger particles will have asand-paper type effect resulting in both a rough feel as well as ashortened life for the fabric owing to constant rubbing of the particlesagainst the fiber or fibril strands which may cause premature wear andcompromise the overall strength and other properties of the fabric.Exemplary encapsulated antimicrobial materials and their methods ofmanufacture are described in Trogolo et. al.—U.S. Pat. No. 7,357,949,which is incorporated herein by reference.

The antimicrobial agent, whether encapsulated or not, may be applied byany of the methods known in the art, including dusting, spraying,brushing, rolling, printing, dipping and the like. The exact method willdepend, in part, upon a number of variables such as the type ofantimicrobial agent employed, the type of fabric to be treated, whethera binder is employed or not, etc. Regardless of which method isemployed, the antimicrobial will preferably be applied so as to providefrom 0.05 g to 2 g antimicrobial metal, preferably from 0.1 to 1 gantimicrobial metal, more preferably from 0.2 g to 0.6 g antimicrobialmetal, per meter² of fabric. Lower levels are often insufficient toimpart good antimicrobial efficacy and higher levels, though perhapsproviding more immediate and a higher level of efficacy, are oftenunnecessary and add to the cost. From a commercial perspective, onepreferably, balances the cost of the material with the speed and degreeof performance warranted. For example, one may use a lower loading oramount of antimicrobial agent in the case of run-of-the-mill socks andunderwear available are one's low end consumer retail store and a higherloading in the same type of products, though now a designer brand, soldthrough a high end, premium retail store. Similarly, disposable and/orlimited life garments may employ lower levels of the antimicrobial agentsince longevity of efficacy is not an issue.

As noted, there are multiple ways by which the antimicrobial agent isapplied to the fabric. For example, one may apply the antimicrobialagent as a dry powder, either dusting the fabric or combining the twoand then subjecting the dusted or combined materials to tumbling andother mechanical action whereby the particles become entrapped in theweave and/or interstitial spaces in the fabric. Similarly, theantimicrobial agent may be applied as a suspension, dispersion or likecomposition in a suitable, neutral solvent to the fabric or combinedwith the fabric and then subjected to agitation where, again, theantimicrobial agent becomes entrapped in the weave and/or interstitialspaces in the fabric as the solvent evaporates leaving the antimicrobialagent in place. The neutral solvent, which may, be water or an aqueousbased liquid, e.g., water-alcohol solution, is one that does not affectthe fabric and merely carries the antimicrobial agent before evaporatingoff. These methods, while effective are less desirable as retention ofthe antimicrobial agent is reliant upon mechanical entrapment andsubsequent washing will tend to lead to the dislodgement and loss of theentrapped particles.

Alternatively, a suspension, dispersion or like composition of theantimicrobial agent in a suitable, volatile solvent may be applied tothe fabric except here the solvent is one that causes a swelling orsoftening of the composition of the fabric. In this manner, theparticles of the antimicrobial agent become bonded, embedded and/orimpregnated into the swelled or tackified surface layer of the fabricand, is deposited or affixed thereto once the solvent evaporates and theswelling and/or tackiness subsides.

Preferably, the antimicrobial agent is applied by treating the fabricwith a coating composition comprising the antimicrobial agent and abinder. The coating composition may be a 100% solids based compositionor a “solvent” based system such as true solutions, dispersions orcolloids. 100% solid compositions are flowable compositions that cure orset upon exposure to the atmosphere or other curing conditions. Whileavoiding the environmental, health and safety concerns associated withthe use of solvents, 100% solids binder compositions oftentimes sufferfrom higher viscosity and, therefore, can be more difficult to employwith textiles, especially where the intent is to get a thin even coatingof the antimicrobial agent on the textile surface without adding bulk tothe individual fibers or filaments or the textiles as a whole.

Binder systems are well known and are currently used for altering and/orproviding other textile modifiers to the surfaces of textiles.Especially suited binders are commonly referred to as finishing agentsfor the textile industry. While it appears that the preferred bindersare those based on polyurethanes or acrylics, especially anionic orlightly anionic acrylics, in practice essentially any effectivecationic, anionic, or non-ionic binder resin may be used. Mostpreferably, the binder resin is non-ionic or slightly anionic. Suitablenon-ionic binders include those based on polyurethane such as thoseavailable from BASF under the tradename Lurapret as well as binderresins selected from the group consisting of non-ionic permanent pressbinders (i.e., cross-linked adhesion promotion compounds) including,without limitation, cross-linked imidazolidinones such as thoseavailable from Sequa under the tradename Permafresh. Anionic andslightly anionic binders include various acrylics, such as RhoplexTR3082 from Rohm & Haas and those sold by BASF under the tradenameHelizarin. Other potential binder resins include, but are not limited tomelamine formaldehyde, melamine urea, ethoxylated polyesters (such asLubril QCX from Rhodia), and the like. Oftentimes there binders willalso contain other surfactants, leveling agents and the like. Preferredbinder systems are those having an aqueous or aqueous-based carrier orsolvent.

Typically the binder system will comprise from about 0.1 to about 60weight percent, most preferably from about 1 to about 40 weight percentof the antimicrobial agent based on the total weight of bindercomposition or system. The amount of each component of the antimicrobialagent and the ratio thereof in the solidified binder resin will be asset forth above. These antimicrobial binder systems may also contain oneor more co-constituents for modifying or altering the textile surface orproperties. For example, the antimicrobial binder system may furtherinclude UV or thermal stabilizers, adhesion promoters, leveling agents,odor absorbing agents, sizing agents, thickeners and the like. Each willbe present in their traditional amounts for the particular textile orend-use application thereof.

The antimicrobial binder systems may be applied by any of the methodsknown in the art, including spraying, brushing, rolling, printing,dipping and the like. Typically these antimicrobial binder systems willbe applied so as to provide as thin a coating as possible whileconcurrently providing the needed degree of antimicrobial performance.Such rate of applications will be consistent with the manufacturerstated or art recognized rate of application for the neat (i.e., withoutantimicrobial agent) binder or finishing system. Most preferably, therate of application will be such as to provide from about 0.01 to 20weight percent, preferably from about 0.02 to 10 weight percentantimicrobial binder system based on the combined weight of the bindersystem and textile.

While the foregoing discussion has been on the basis that antimicrobialagent is incorporated into the binder system, those skilled in the artwill also recognize that the antimicrobial agent and binder system maybe applied to the fabric in two separate steps according to twodifferent methodologies. In the first, the fabric is first wetted withthe binder system and the antimicrobial agent dusted onto the wettedsurface. The antimicrobial agent essentially resides on the outersurface of the subsequently cured or hardened binder resin.Alternatively, the surface of the fabric may be dusted with theantimicrobial agent and then the dusted surface treated with the bindersystem: thereby encapsulating or potting the particles of theantimicrobial agent to the textile surface.

Based on the foregoing general discussion of the steps and materialsemployed in the practice of the present teachings, it is to beappreciated that the process may involve a number of different elementsand iterations. For example, the process may be conducted in a singlevessel in which the fabric is immersed in each of the respectivesolutions and/or compositions. Alternatively the vessel could be of thetype that allows for a continuous or intermittent spray of the solutionsor compositions while the fabric is being tumbled, agitated and/or spun.A single vessel may be capable of both actions, as with acommercial/-consumer washing machine. While such single vessel batchmethod is suitable for small scale processes, larger scale processeswill preferably employ a plurality or series of vessels, each dedicatedto a single or perhaps two of the steps of the process or, as also notedabove, a single step may employ a plurality of vessels, especially therinse step. To assist in such a process, the fabrics could be placed ina basket that is lowered into each vessel and then retracted once theprocessing in that vessel is completed. Preferably, this basket would becapable of spinning to add centrifugal forces to the fabric so as toeffectively spin out the liquids. In this case, the vessel may be ofsuch depth that the basket is raised from the liquid, without removal offrom the vessel, and spun so that the effluent from the spinning remainsin the vessel and falls back into the bulk of the liquid. Generallyspeaking, those skilled in the art, with the benefit of the abovedescribed teachings will readily appreciate the multitude of varioussystems that could be devised to maximize the efficiency of the processfor the particular need of the person or entity employing the same.

The present teachings also provide for an antimicrobial fabric,preferably one having both antimicrobial and anti-odor characteristics.The present teachings especially provide for antimicrobial fabricsderived or made from sulfur-containing fabrics, particularly thosetreated by the method of the invention. This is especially beneficialand surprising inasmuch as, up to now, it has been difficult, if notimpossible, or nearly so, to impart suitable antimicrobial activity tosulfur-containing fabrics. It has been especially difficult to have anypermanence to the antimicrobial activity when the sulfur-containingfabrics are subjected to repeated washings. In particular, the presentteachings provide antimicrobial efficacy, preferably to at least a onelog reduction, preferably a two log reduction, most preferably a threelog reduction in, e.g., Staph aureus and/or Klebsiella pneumoniae after20 washings, preferably after 30 washings as measured by AATCC 100. Thecurrent invention solves this problem. Fabrics prepared by the method ofthis invention enhance and expand the many and varied uses ofsulfur-containing fabrics.

The following examples merely illustrate the invention. Those skilled inthe art will recognize many variations that are within the spirit of theinvention and scope of the claims.

EXAMPLE 1

A series of evaluations of the claimed method were performed on 10″ by12″ samples of dyed denim fabric. The samples evaluated were indigo dyed(ID), sulfur tops (ST—indigo dyed and then sulfur dye), sulfur bottom(SB—sulfur dye and then indigo dye) and pure sulfur (PS—no indigo dye).Each sample was placed in a 1 L flask containing 325 g of an aqueoussolution of 7% by weight aluminum sulfate. The contents were agitatedfor 45 minutes on a laboratory shaker. The fabric is then removed fromthe flask and agitated in a pail for five minutes with 3 L of water at35° C. The water is drained, 3 L of fresh water at 35° C. is added andthe mixture agitated for five minutes. The fabric is removed andagitated in a pail for ten minutes with a solution of 3 g sodiumcarbonate in 3 L of water at 35° C. The solution is drained, 3 L offresh water at 35° C. is added and the mixture agitated for fiveminutes. The fabric is removed and dried for 45 minutes in a clothesdryer set at high. The fabric is placed in a tumbling cylinder and asolution, of an aqueous acrylic based binder system containing 20% byweight of a 60:40 combination of silver/copper zeolite (grade AC1ODavailable from Sciessent LLC, Wakefield, Mass.): silver/zinc zeolite(grade AJ10D available from Sciessent LLC, Wakefield, Mass.) is meteredin by spraying as a mist over a period of about ten minutes to give aloading of 0.3 g combined metal per square meter of fabric. Followingapplication, the fabric is heated for 3.5 minutes at 150° C. to dry thefabric and cure the binder.

Portions of each sample were then washed 30 times in a standard washingmachine set at regular wash setting with three ounces of Tide laundrydetergent. The antimicrobial efficacy of the washed and unwashed sampleswas then determined in accordance with the Dow Shaker Test (ASTM E2149).Specifically, approximately a 0.5 g sample of each fabric was placed inan individual receptacle containing 25 mL of an inoculum buffer having1.09×10⁵ CFU/mL of Staphylococcus aureus (Staph a.), as determined byplate count enumeration. The receptacles were placed on a shaker andmaintained at room temperature for 24 hours. An organism count was thenmade of the original inoculum as well as the inoculum from the samplesand the percent reduction (based on the original inoculum) determined.In similar fashion antimicrobial efficacy was tested using Kleb.pneumoniae (Kleb p.) as well. The specific tests and the resultsattained thereby are presented in Table 1.

The results shown in Table 1 demonstrate the marked and surprisingimprovement in antimicrobial performance with those fabric samples whichhave undergone the aluminum treatment.

EXAMPLE 2

10″ by 12″ samples of denim were treated in a similar fashion to thesamples in Example 1, but using different concentrations and duration aswell as different levels of the antimicrobial treatment. Followingapplication, the amount of available antimicrobial metal ion wasevaluated by soaking the fabric and determining the metal ion content ofthe solution. The results are presented in Table 2.

TABLE 1 Staph a. (% reduction) Kleb p. (% reduction) Fabric AM AlSO₄ 0wash 30 wash 0 wash 30 wash ID Yes Yes 99.998 99.998 99.999 99.999 ID NoNo No reduc. No reduc. SB Yes Yes 99.998 99.95 99.999 99.99 SB No No Noreduc. No reduc. ST Yes Yes 99.91 87.24 99.999 98.07 ST No Yes 51.0372.14 ST No No No reduc No reduc PS Yes Yes 99.89 69.41 99.999 27.5* PSNo No No reduc. 66.76 No reduc. 32.5 *Sample was contaminated

TABLE 2 AlSO₄ Ag (ppb) Cu (ppb) Concentration Time AM* 0 wash 0 wash10%   5 min 0.4 370 430 10%  80 min 0.4 210 260 none 0.4 12 21 1%  5 min0.3 68 52 4%  5 min 0.3 70 94 none 4 8 5% 45 min 0.3 180 380 *weight ofantimicrobial metal per square meter of material

The results presented in Table 2 demonstrate the marked improvement inthe retention of the antimicrobial metal treatment with those fabricsamples which have been subjected to the aluminum treatment.

EXAMPLE 3

A second series of evaluations of the claimed method were performed on2″×2″ samples of denim pant legs, this time adding a sodium percarbonatepretreatment. The pant legs evaluated were indigo dyed (ID), sulfur tops(ST—indigo dyed and then sulfur dye) and sulfur bottom (SB—sulfur dyeand then indigo dye). Before subjecting the pant legs to the presentprocess, the pant legs were desized with amylase enzymes andstonewashed. The same test procedure was then performed, as follows, onfour samples of each pant leg.

As a pretreatment, each pant leg was placed in a Unimac dying machineand containing 30 liters of a 1.6% aqueous solution of sodiumpercarbonate at 45° C. for 20 minutes. The pant legs were then removedfrom the sodium percarbonate solution and washed with clean water 2× atabout 40° C. The pant legs were then submerged in a 6% aqueous solution(˜30 liters) of aluminum sulfate hydrate at 45° C. for 20 minutes(approx. pH of 3.5). The pant legs were then removed from the aluminumsulfate solution and washed with clean water 2× at about 40° C. (approx.pH 4.0). The pant legs were then subjected to centrifugation to removeexcess water, bringing the water content down to about 60%. Theantimicrobial treatment from Example 1 was then applied using a Tonellomachine by spray 10 seconds on, 20 seconds off, to apply approximately0.4 grams of metal ion per square meter of fabric; however, the indigosamples without the sodium percarbonate/aluminum sulfate treatmentreceived double the volume of the antimicrobial solution, ˜0.8grams/meter². Finally, the treated pant legs were dried. The treated anduntreated samples were then subjected to antimicrobial performanceevaluations in accordance with AATCC100 using Staph aureus as the testorganism, both before and after 30 washes, 24 hour contact. The testsamples and results are presented in Table 3, where the individualresults represent the average of the four test samples.

TABLE 3 Staph a. (% reduction) Fabric NaPer/AlSO₄ AM 0 wash 30 wash IDNo No No reduc. No reduc. ID No Yes 99.9998 99.99 ID Yes Yes 99.9999*99.997 SB Yes Yes 99.9998 99.99 ST Yes Yes 99.88 99.9 *one samplecontaminated and ignored

The results shown in Table 3 demonstrate the longevity of theperformance of the antimicrobial agent, even with washing. Although theperformance benefit between the sodium percarbonate/aluminum sulfatepretreatment and those not subjected to the pretreatment appears minimalin a percent reduction standpoint, any reduction in terms of bacteria isimportant.

EXAMPLE 4

The experiment of Example 3 was repeated with samples of sulfur bottoms;however, following the washing before application of the antimicrobialagent, the fabric was dried so that the wet antimicrobial compositionwas applied to a wet fabric. In this instance, at zero washings thetreatment provided a 99.999% reduction and a 99.96 reduction after 30washings.

EXAMPLE 5

A series of experiments were conducted in accordance with the procedureset forth in Example 3 to show the impact of the percarbonatepretreatment. Each sample was treated with the 6% aluminum sulfatesolution and the 0.4 g/m² antimicrobial application. In this example,the sodium percarbonate solution, if used, was reduced to a 0.9%concentration. Additionally, the microbiological testing was conductedwith two test organisms, S. aureus and Kleb. pneumoniae. The testsamples and the results, the average of two test results, are shown inTable 4.

TABLE 4 Staph a. (% reduction) Kleb p. (% reduction) Fabric NaPer 0 wash30 wash 0 wash 30 wash ST No No reduc. 80 No reduc. 87.6 ST Yes 86.5 2378.9 94.9 SB No 83.1 96.9 98.1 97.4 SB Yes 99.6 99.96 99.995 99.9995

The results presented in Table 4 clearly show the benefit of the addedcarbonate pretreatment.

Although the process and prepared articles of the present specificationhave been described with respect to specific embodiments and examples,it should be appreciated that the present teachings are not limitedthereto and other embodiments utilizing the concepts expressed hereinare intended and contemplated without departing from the scope of thepresent teaching. Thus the true scope of the present teachings isdefined by the claimed process steps and any and all modifications,variations, or equivalents that fall within the spirit and scope of theunderlying principles set forth herein.

I claim:
 1. An antimicrobial fabric comprising a sulfur-containingfabric that has been subjected to the following steps in the orderpresented: a) treating the fabric with an aluminum salt solutioncomprising an aluminum salt capable of sequestering, binding and/orreacting with sulfur and sulfur-containing species; b) rinsing thetreated fabric with water or another suitable solvent to remove thealuminum salt from the fabric to give a rinsed fabric; and c) treatingthe rinsed fabric with an antimicrobial metal-ion type antimicrobialagent, said antimicrobial fabric having improved antimicrobialperformance as compared to the same sulfur-containing fabric that hasnot been subjected to steps (a) and (b) prior to treatment with theantimicrobial metal-ion type antimicrobial agent.
 2. The antimicrobialfabric of claim 1 which has been treated with an aqueous solution of anoxidizing agent prior to or concurrent with the treatment of the fabricwith the aluminum salt.
 3. The antimicrobial fabric of claim 2 whereinthe oxidizing agent is selected from hydrogen peroxide, percarbonates,bromates, chlorates, persulfates, perborates, and hydrates thereof andcombinations thereof.
 4. The antimicrobial fabric of claim 2 wherein theoxidizing agent is a hydrate of sodium percarbonate.
 5. Theantimicrobial fabric of claim 1 wherein the sulfur-containing fabric wasone that had been treated with a sulfur dye.
 6. The antimicrobial fabricof claim 1 wherein the sulfur-containing fabric was one that had beentreated with a combination of indigo and a sulfur dye.
 7. Theantimicrobial fabric of claim 1 wherein fabric is selected from cotton,denim, and wool.
 8. The antimicrobial fabric of claim 1 wherein thefabric is denim.
 9. The antimicrobial fabric of claim 1 wherein thefabric is in the form of apparel made from denim.
 10. The antimicrobialfabric of claim 1 wherein the fabric is in the form of pair of bluejeans.
 11. The antimicrobial fabric of claim 1 wherein the fabric iswool.
 12. The antimicrobial fabric of claim 1 wherein the aluminum saltcontains an anion selected from sulfate, carboxylate, phosphate, andhydroxide.
 13. The method antimicrobial fabric of claim 1 wherein thealuminum salt is a hydrate.
 14. The antimicrobial fabric of claim 10wherein the aluminum salt is selected from aluminum sulfate and hydratesof aluminum sulfate.
 15. The antimicrobial fabric of claim 1 wherein theantimicrobial agent is present at a level of from 0.05 g to 1 gantimicrobial metal per meter² of fabric.
 16. The antimicrobial fabricof claim 1 wherein the antimicrobial agent is present at a level to offrom 0.2 g to 0.6 g antimicrobial metal per meter² of fabric.
 17. Theantimicrobial fabric of claim 1 wherein the antimicrobial agent is asource of silver ions and copper ions and the weight ratio of silverions to copper ions is from 1:10 to 10:1.
 18. The antimicrobial fabricof claim 1 wherein the antimicrobial agent is an ion-exchange typeantimicrobial agent having both ion-exchanged silver and copper ions.19. The antimicrobial fabric of claim 18 wherein the ion-exchange typeantimicrobial agent is a zeolite having ion-exchanged silver and copperions.
 20. The antimicrobial fabric of claim 1 wherein a binder systembinds the antimicrobial agent to the fabric.